Overvoltage protection circuit, switching power supply circuit and device

Abstract

The invention relates to the technical field of communication, and discloses an overvoltage protection circuit and device and a communication product, the overvoltage protection circuit is used for providing overvoltage protection for a master control IC chip, a master control power supply circuit is connected with the voltage output end of a VCC controller, and a voltage division sampling circuit is communicated with a VIN power supply; the main control power supply circuit supplies power to the LLC controller through a triode; the voltage division sampling circuit is connected with the reference end of the three-terminal regulator; the control circuit is communicated with the main control power supply circuit, the control circuit is connected with a first MOS tube, the control circuit is connected with a grid electrode of the first MOS tube, a drain electrode of the first MOS tube is connected with a base electrode of the triode, and a source electrode of the first MOS tube is grounded; the cathode of the three-terminal regulator is connected with the control circuit; the anti-oscillation circuit is connected with the control circuit, a second MOS tube is arranged on the anti-oscillation circuit, and the second MOS tube is connected with the reference end of the three-end voltage stabilizer through a first resistor; the first resistor and the second MOS tube are connected in parallel with the voltage division sampling circuit through the second resistor. The problem of power output oscillation in the prior art is solved.

Description

Technical Field

[0001] The present application relates to the technical field of power supply circuits, and more particularly to an overvoltage protection circuit, a switching power supply circuit and a device. Background Art

[0002] In the prior art, input overvoltage protection circuits often use op amp hysteresis comparators to achieve overvoltage protection functions, but the existing op amp circuit components are high in cost and the PCB layout (printed circuit board layout) occupies a large area, which is not convenient for miniaturization. Moreover, in the prior art, when the input voltage is the set OVP (overvoltage protection) value, the overvoltage protection circuit is always in a hiccup state, repeatedly switching quickly and causing the power supply output to oscillate, affecting the service life of the corresponding product. Summary of the invention

[0003] The present application provides an overvoltage protection circuit, a switching power supply circuit and a device, aiming to solve the problem in the prior art that when the input voltage is a set OVP (overvoltage protection) value, the overvoltage protection circuit is always in a hiccup state, repeatedly switching quickly and causing power supply output oscillation.

[0004] In one solution, an overvoltage protection circuit is provided for providing overvoltage protection for a main control IC chip, including: a main control power supply circuit, a voltage division sampling circuit, a control circuit, and an anti-oscillation circuit;

[0005] Wherein, the main control power supply circuit is connected to the voltage output terminal of the VCC controller, and the voltage division sampling circuit is connected to the VIN power supply;

[0006] The main control power supply circuit supplies power to the LLC controller through a transistor; the voltage division sampling circuit is connected to the reference end of the three-terminal regulator;

[0007] The control circuit is connected to the main control power supply circuit, and the control circuit is connected to a first MOS tube, the control circuit is connected to the gate of the first MOS tube, the drain of the first MOS tube is connected to the base of the triode, and the source of the first MOS tube is grounded; the cathode of the three-terminal regulator is connected to the control circuit;

[0008] The anti-oscillation circuit is connected to the control circuit, a second MOS tube is provided on the anti-oscillation circuit, and the second MOS tube is connected to the reference end of the three-terminal regulator through a first resistor; the first resistor and the second MOS tube are connected in parallel with the voltage divider sampling circuit through a second resistor.

[0009] Among them, the anode of the three-terminal regulator is grounded; a second resistor is connected to the voltage-dividing sampling circuit, the first resistor and the second resistor are connected in parallel to enter the voltage-dividing sampling circuit, a second MOS tube is provided on the path of the first resistor, the drain of the second MOS tube is connected to the first resistor, the source of the second MOS tube is grounded, and the gate of the second MOS tube is connected to the anti-oscillation circuit; the emitter and collector of the triode are connected to the main control circuit in sequence.

[0010] The power supply of the main control power supply circuit comes from the voltage output of the VCC controller, wherein the output end of the VCC controller is connected to the PFC controller to provide power to the PFC controller.

[0011] In one solution, resistors are connected to the main control power supply circuit, the voltage division sampling circuit, the control circuit, and the anti-oscillation circuit.

[0012] In one embodiment, the voltage-dividing sampling circuit is connected to a first capacitor, and the first capacitor is connected in parallel with the second resistor.

[0013] In one solution, a second capacitor is further provided on the control circuit, and one end of the second capacitor is connected to the gate of the first MOS tube, and the other end is grounded.

[0014] In one solution, a voltage stabilizing capacitor is provided on the main control power supply circuit, and one end of the voltage stabilizing capacitor is connected to the main control power supply circuit after the emitter of the transistor, and the other end is grounded.

[0015] In one solution, one end of the main control power supply circuit is connected to a VCC controller.

[0016] In one solution, the three-terminal regulator is of AZ431 type, and the first MOS tube and the MOS tube are both of 2N7002 type.

[0017] In one embodiment, the VIN power supply is obtained by filtering and rectifying the input power supply, and the voltage of the input power supply is 90V-264V AC.

[0018] In one embodiment, a switching power supply circuit is provided, wherein the switching power supply circuit includes the overvoltage protection circuit.

[0019] In one embodiment, an overvoltage protection device is provided, and the overvoltage protection device includes the switching power supply circuit.

[0020] Beneficial effects of this application:

[0021] The connection and disconnection of the triode are realized by setting the cooperation of the three-terminal voltage regulator and the first MOS tube, thereby conditionally controlling the connection and disconnection of the main control power supply circuit, thereby ensuring the working safety of the LLC controller.

[0022] At the same time, a second MOS tube, a first resistor and a second resistor are provided to adjust the resistance value of the lower bias resistor of the three-terminal regulator, that is, when the input voltage exceeds the OVP (overvoltage protection) value, after the three-terminal regulator is turned off, the first resistor and the second resistor are released from the parallel state, so the reference end resistance of the three-terminal regulator becomes larger, that is, the lower bias resistor increases. Therefore, when the input voltage decreases, the input voltage must be lower than the OVP value to turn off the three-terminal regulator again, and the power supply resumes working. This recovery voltage must be lower than the OVP point, forming a hysteresis, so as to prevent the three-terminal regulator from being in a hiccup state when the input voltage is at the OVP critical point. The transistor repeatedly switches quickly to cause the power supply output to oscillate, thereby improving the service life of the corresponding product. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 This is an overvoltage protection circuit diagram in one embodiment of the present application;

[0025] Figure 2 This is a schematic diagram of an overvoltage protection process in an embodiment of the present application;

[0026] Figure 3 This is a circuit diagram of a VCC controller in one embodiment of the present application;

[0027] Figure 4 This is a circuit diagram of an LLC controller in one embodiment of the present application;

[0028] Figure 5 is a circuit diagram of a PFC controller in an embodiment of the present application;

[0029] Reference numerals in the figures:

[0030] 1. Main control power supply circuit; 11. Transistor; 12. Voltage stabilizing capacitor; 2. Voltage division sampling circuit; 21. Three-terminal voltage regulator; 22. First capacitor; 3. Control circuit; 31. First MOS tube; 32. Second capacitor; 4. Anti-oscillation circuit; 41. Second MOS tube; 42. First resistor; 43. Second resistor; 5. PFC controller; 6. LLC controller; 7. VCC controller. DETAILED DESCRIPTION

[0031] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0032] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0033] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0034] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0036] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0037] The present application makes improvements and innovations and proposes the following embodiments.

[0038] In some embodiments, see Figures 1 to 5 , an overvoltage protection circuit is provided, which is used to provide overvoltage protection for the main control IC chip, including: a main control power supply circuit 1, a voltage division sampling circuit 2, a control circuit 3, and an anti-oscillation circuit 4;

[0039] Among them, the main control power supply circuit 1 is connected to the voltage output terminal of the VCC controller 7, and the voltage division sampling circuit 2 is connected to the VIN power supply;

[0040] The main control power supply circuit 1 supplies power to the LLC controller 6 through the transistor 11; the voltage division sampling circuit 2 is connected to the reference end of the three-terminal regulator 21;

[0041] The control circuit 3 is connected to the main control power supply circuit 1, and the control circuit 3 is connected to the first MOS transistor 31, the control circuit 3 is connected to the gate of the first MOS transistor 31, the drain of the first MOS transistor 31 is connected to the base of the transistor 11, and the source of the first MOS transistor 31 is grounded; the cathode of the three-terminal regulator 21 is connected to the control circuit 3;

[0042] The anti-oscillation circuit 4 is connected to the control circuit 3. A second MOS tube 41 is provided on the anti-oscillation circuit 4, and the second MOS tube 41 is connected to the reference end of the three-terminal regulator 21 through a first resistor 42; the first resistor 42 and the second MOS tube 41 are connected in parallel with the voltage divider sampling circuit 2 through a second resistor 43.

[0043] Among them, the anode of the three-terminal regulator 21 is grounded; a second resistor 43 is connected to the voltage-dividing sampling circuit 2, a first resistor 42 and a second resistor 43 are connected in parallel to enter the voltage-dividing sampling circuit 2, a second MOS tube 41 is provided on the path of the first resistor 42, the drain of the second MOS tube 41 is connected to the first resistor 42, the source of the second MOS tube 41 is grounded, and the gate of the second MOS tube 41 is connected to the anti-oscillation circuit 4; the emitter and collector of the transistor 11 are connected to the main control circuit in sequence; the "VIN (Voltage Input) power supply" is connected to the positive end of the DC output of the rectifier bridge, and the power supply of the main control power supply circuit 1 comes from the voltage output of the VCC controller 7, wherein the output end of the VCC controller 7 is connected to the PFC controller 5, and the VCC controller 7 is used to provide power to the PFC controller.

[0044] like Figure 1 As shown, the VIN power supply reference source has a certain voltage value after being divided by resistors R123, R46, R137, and R136.

[0045] When the VIN input voltage is within the rated range, the sampling voltage obtained at the reference end of the three-terminal regulator 21 is lower than the reference voltage of 2.5V, and the three-terminal regulator 21 is turned off. The voltage provided by the VCC controller 7 drives the first MOS tube 31 to be turned on through the resistor R134, the resistor R140, and the resistor R139, and the base of the transistor 11 is grounded through the resistor R141. Since the transistor 11 is a PNP transistor 11, the transistor 11 is turned on at this time, and the main control power supply circuit 1 is connected, that is, the VCC controller supplies power to the LLC controller 6 (main control IC), and the power supply works normally.

[0046] At the same time, the voltage output by the VCC controller is divided by the resistors R134, R138, and R133 to drive the second MOS tube 41 to turn on. After the second MOS tube 41 is turned on, the reference end of the three-terminal regulator 21 is connected to the second resistor 43 (i.e., resistor R136) and the first resistor 42 (i.e., resistor R135) connected in parallel. The resistance value of the reference end of the three-terminal regulator 21 is smaller than that of the first resistor 42 or the second resistor 43 connected alone, so the voltage of the reference end of the three-terminal regulator 21 becomes smaller.

[0047] When the VIN input voltage exceeds the set OVP value, the sampling voltage obtained by the reference end of the three-terminal regulator 21 is higher than the reference voltage of 2.5V, so the three-terminal regulator 21 is turned on, and the current of the VCC controller is turned on and grounded through the three-terminal regulator 21, causing the gate of the first MOS tube 31 to become a low level, and the first MOS tube 31 is turned off, so the transistor 11 is also turned off. At this time, the VCC controller cannot supply power to the LLC controller 6 (main control IC), and the power supply stops working; at the same time, because the VCC controller The current of the regulator is connected to the ground through the three-terminal regulator 21, the gate of the second MOS tube 41 also becomes a low level, the second MOS tube 41 is turned off, and the first resistor 42 and the second resistor 43 are disconnected from the parallel connection, that is, the reference end of the three-terminal regulator 21 is connected to the second resistor 43. At this time, the resistance value of the reference end of the three-terminal regulator 21 is greater than the resistance value of the second resistor 43 (i.e., resistor R136) and the first resistor 42 (i.e., resistor R135) connected in parallel. Since the resistance value of the reference end of the three-terminal regulator 21 increases, the voltage of the reference end of the three-terminal regulator 21 increases (compared with the case where the second resistor 43 (i.e., resistor R136) and the first resistor 42 (i.e., resistor R135) are connected in parallel), and it is more difficult to achieve shutdown.

[0048] Therefore, the three-terminal regulator 21 can be turned off only when the VIN input voltage is reduced to a lower level (lower than the VIN input voltage required when the three-terminal regulator 21 can be turned on when the second resistor 43 and the first resistor 42 are connected in parallel).

[0049] The first resistor 135 and the second MOS tube 41 can increase the voltage value range of the VIN input voltage to start the short-circuit protection circuit, so as to prevent the three-terminal regulator 21 from being in a hiccup state when the VIN input voltage is at the OVP critical point, and the transistor 11 repeatedly switches quickly to cause power supply output oscillation.

[0050] The three-terminal regulator 21 and the first MOS tube 31 are arranged to cooperate with each other to realize the connection and disconnection of the transistor 11 , thereby conditionally controlling the connection and disconnection of the main control power supply circuit 1 , thereby ensuring the working safety of the LLC controller 6 .

[0051] At the same time, a second MOS tube 41, a first resistor 42 and a second resistor 43 are provided to adjust the resistance value of the lower bias resistor of the three-terminal regulator 21, that is, when the input voltage exceeds the OVP (overvoltage protection) value, after the three-terminal regulator 21 is turned off, the first resistor 42 and the second resistor 43 are released from the parallel state, so the reference end resistance of the three-terminal regulator becomes larger, that is, the lower bias resistor increases. Therefore, when the input voltage decreases, the input voltage must be lower than the OVP value to turn off the three-terminal regulator 21 again, and the power supply resumes working. This recovery voltage must be lower than the OVP (overvoltage protection) point to form a hysteresis, so as to prevent the three-terminal regulator 21 from being in a hiccup state when the input voltage is at the OVP critical point, and the transistor 11 repeatedly switches quickly to cause the power supply output to oscillate, thereby improving the service life of the corresponding product.

[0052] In some embodiments, resistors are connected to the main control power supply circuit 1, the voltage division sampling circuit 2, the control circuit 3, and the anti-oscillation circuit 4. The resistors are provided for voltage division so that the corresponding components can obtain appropriate voltage values.

[0053] Specifically, Figure 1 As shown, the control circuit 3 is also connected to a voltage VCC2 , and the control circuit 3 is also connected to a resistor R139 , and one end of the resistor R139 is connected to the control circuit 3 , and the other end is grounded. The resistor R139 is used to divide the gate voltage of the first MOS tube 31 .

[0054] In some embodiments, the voltage-dividing sampling circuit 2 is connected to a first capacitor 22, and the first capacitor 22 is connected in parallel with the second resistor 43. The capacitor can filter the current in the circuit, reduce the interference of the VIN input voltage clutter on the three-terminal regulator 21, and reduce the misconduction of the three-terminal regulator 21.

[0055] In some embodiments, the control circuit 3 is further provided with a second capacitor 32, and one end of the second capacitor 32 is connected to the gate of the first MOS transistor 31, and the other end is grounded. The capacitor can filter the current in the circuit, reduce the interference of the clutter in the output voltage of the VCC controller 7 on the first MOS transistor 31, and reduce the misconduction of the first MOS transistor 31.

[0056] In some embodiments, a voltage stabilizing capacitor 12 is provided on the main control power supply circuit 1, and one end of the voltage stabilizing capacitor 12 is connected to the main control power supply circuit 1 located after the emitter of the transistor 11, and the other end is grounded. The voltage stabilizing capacitor 12 can filter the voltage input to the LLC controller 6, and can also store energy for the voltage input to the LLC controller 6.

[0057] In some embodiments, one end of the main control power supply circuit 1 is connected to a VCC controller 7. The VCC controller 7 can output a stable voltage used by the LLC controller 6.

[0058] In some embodiments, the three-terminal voltage regulator 21 is of AZ431 type, and the first MOS tube 31 and the MOS tube are both of 2N7002 type, which can increase the service life of the overvoltage protection circuit.

[0059] In some embodiments, the VIN power supply is obtained by filtering and rectifying the input power supply, and the voltage of the input power supply is: 90V-264V AC. The voltage range applicable to the circuit fully covers the AC power on the market. The power supply is easy to obtain.

[0060] In some embodiments, a switching power supply circuit is provided, and the switching power supply circuit includes the overvoltage protection circuit. The beneficial effect is the same as that of the overvoltage protection circuit, and will not be described in detail here.

[0061] In some embodiments, an overvoltage protection device is provided, and the overvoltage protection device includes the switch power supply circuit. The beneficial effect is the same as that of the overvoltage protection circuit, and will not be repeated here.

[0062] The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An overvoltage protection circuit, used to provide overvoltage protection for a main control IC chip, characterized in that: include: Main control power supply circuit, voltage division sampling circuit, control circuit, anti-oscillation circuit; Wherein, the main control power supply circuit is connected to the voltage output terminal of the VCC controller, and the voltage division sampling circuit is connected to the VIN power supply; The main control power supply circuit supplies power to the LLC controller through a transistor; the voltage division sampling circuit is connected to the reference end of the three-terminal regulator; The control circuit is connected to the main control power supply circuit, and the control circuit is connected to a first MOS tube, the control circuit is connected to the gate of the first MOS tube, the drain of the first MOS tube is connected to the base of the triode, and the source of the first MOS tube is grounded; the cathode of the three-terminal regulator is connected to the control circuit; The anti-oscillation circuit is connected to the control circuit, a second MOS tube is provided on the anti-oscillation circuit, and the second MOS tube is connected to the reference end of the three-terminal regulator through a first resistor; the first resistor and the second MOS tube are connected in parallel with the voltage divider sampling circuit through a second resistor.

2. The overvoltage protection circuit according to claim 1, characterized in that: The main control power supply circuit, the voltage division sampling circuit, the control circuit and the anti-oscillation circuit are all connected with resistors.

3. The overvoltage protection circuit according to claim 1, characterized in that: The voltage-dividing sampling circuit is connected to a first capacitor, and the first capacitor is connected in parallel with the second resistor.

4. The overvoltage protection circuit according to claim 1, characterized in that: The control circuit is also provided with a second capacitor, and one end of the second capacitor is connected to the gate of the first MOS tube, and the other end is grounded.

5. The overvoltage protection circuit according to claim 4, characterized in that: A voltage stabilizing capacitor is provided on the main control power supply circuit, and one end of the voltage stabilizing capacitor is connected to the main control power supply circuit after the emitter of the transistor, and the other end is grounded.

6. The overvoltage protection circuit according to claim 1, characterized in that: One end of the main control power supply circuit is connected to a VCC controller.

7. The overvoltage protection circuit according to claim 1, characterized in that: The three-terminal voltage regulator is of AZ431 type, and the first MOS tube and the MOS tube are both of 2N7002 type.

8. The overvoltage protection circuit according to claim 1, characterized in that: The VIN power supply is obtained by filtering and rectifying the input power supply, and the voltage of the input power supply is: 90V-264V AC.

9. A switching power supply circuit, characterized in that: The switching power supply circuit includes the overvoltage protection circuit according to any one of claims 1-8.

10. An overvoltage protection device, characterized in that: The overvoltage protection device comprises the switching power supply circuit as claimed in claim 9.

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